For adjusting resistance of a chip resistor, there is widely known to form trimming slots in its resistive element. There are conventionally known, for example as shown in FIGS. 9(A) and 9(B), trimming slots 93a formed as linear cuts at generally right angles to the direction of the current flowing through a resistive element 92 from a pair of top electrodes 91 disposed on the top surface of an insulating substrate 90 on both ends, and a trimming slot 93b formed as an L-shaped cut. Disadvantageously, the flow of the current 94 is turbulent at the tip or at the L-shaped bend of these trimming slots to cause local heat generation due to current constriction or change in resistance due to development of microcracks.
In view of the above, there have been proposed various techniques for controlling the problems caused by such current constriction (see Patent Publications 1 to 4).
These prior art trimming slots, however, are formed linearly or in L-shape by first cutting out the slots at generally right angles to the direction of the current flowing through the resistive element, so that it is difficult to sufficiently suppress the current turbulence caused by the trimming slots.
Patent Publication 5 proposes to form a trimming slot by linearly cutting the resistive element in its longitudinal direction over its full length in parallel to the direction of the current flowing through the resistive element. According to this method, the trimming slot is required to be formed even into the electrodes adjacent to the resistive element, in order to inhibit microcracks which tend to form at the tip of the trimming slots. In this case, since the resistive element is not reliably cut out from the electrodes due to the trimming slot, it is difficult to precisely set the resistance during the formation of the trimming slots. In addition, the resistive element is completely divided by the trimming slot in the current-carrying condition, so that the smaller region of the divided resistive element may have risk of current load constriction.